Modular domain walls and gravitational waves

by Xin Wang

Thursday May 28, 2026, 12:00 PM → 1:30 PM Europe/Madrid

IFAE Seminar Room (In-Person)

Modular invariance provides an appealing framework for addressing the flavour puzzle, in which fermion masses and flavour mixing patterns are controlled by a complex modulus field. In this talk, I will first discuss how modulus stabilisation can dynamically drive the modulus towards special fixed points of the modular group, thereby offering a possible origin for the observed flavour structure. I will then focus on the cosmological consequences of this framework, with particular emphasis on modular domain walls. I will describe several representative domain-wall profiles, discuss their formation and collapse in the early Universe, and show how the resulting stochastic gravitational-wave spectra can provide a novel probe of modular flavour symmetry. This establishes a direct connection between flavour phenomenology and early-Universe cosmology. Finally, I will briefly discuss CP-violating modular domain walls.

 

Dr. Xin Wang is currently a postdoctoral researcher at the University of Padua. He received his Ph.D. in theoretical Physics from the Institute of High Energy Physics (IHEP), Chinese Academy of Sciences in 2022. Before joining Padua, he conducted postdoctoral research at Peking University and the University of Southampton. His main research interests lie in particle physics, cosmology and astronomy, with a focus on the origin of neutrino masses and flavour mixing, the evolution of the early Universe, and astrometry-based detection of gravitational waves and dark matter.